#include "../shaderenv.h"

struct fragment
{
	float2 texCoords:  TEXCOORD0; 
};


float2 ComputeBlurFactors(float4 color, float sceneRange, float zFocus)
{
	float2 result;

	const float m = 1.0f;
	const float focalLen = 1.0f;

	const float scale = 5e4f;

	// Compute blur factor based on the CoC size scaled and normalized to 0..1 range
	//float blur = abs(dLens * focalLen * (zFocus - color.w)) / (1e-6f + abs(zFocus * (color.w - focalLen)));

	const float dist = abs(zFocus - color.w);
	const float blur = scale * m * focalLen * dist / (sceneRange * (1e-6f + abs(color.w + dist * step(0, zFocus - color.w))));
	
	//float blur = saturate(blur * scale / maxCoC);
	
	// Depth/blurriness value scaled to 0..1 range
	result = float2(color.w / sceneRange, blur);

	return result;
}


float4 Blur(float4 color, 
			float2 texCoords,
			float2 blurFactors,
			sampler2D colorsTex,
			float2 filterOffs[NUM_DOF_TABS]
			)
{
	float4 avgCol = float4(.0f);
	float total_w = .0f;

	for (int i = 0; i < NUM_DOF_TABS; ++ i)
	{
		float2 sampleTexCoord = texCoords + filterOffs[i] * blurFactors.y;
		float4 sampleCol = tex2Dlod(colorsTex, float4(sampleTexCoord, 0, 0));
		
		// combine the weights
		float w = 1;
		
		avgCol += sampleCol * w;
		total_w += w;
	}

	avgCol /= max(total_w, 1e-6f);

	return avgCol;
}


float4 DepthOfField(fragment IN, 
					uniform sampler2D colorsTex,
					uniform float2 filterOffs[NUM_DOF_TABS],
					uniform float sceneRange,
					uniform float zFocus
					 ): COLOR
{
	// center color
	const float4 color = tex2Dlod(colorsTex, float4(IN.texCoords, 0, 0));
	
	zFocus = min(zFocus, sceneRange * 0.5f);
	float2 blurFactors = ComputeBlurFactors(color, sceneRange, zFocus);

	//float4 outCol = float4(color.x, color.y, blurFactors.y, color.w);
	float4 outCol = Blur(color, IN.texCoords, blurFactors, colorsTex, filterOffs);
	
	return outCol;
}